The present invention relates to a quick connector having a function to verify that a pipe is correctly connected to the quick connector in snap-engagement relation, for example, adapted in assembly in a gasoline fuel piping of an automobile.
In a fluid piping structure, for example, a gasoline fuel piping structure where a tube is joined to a pipe, a connector is used for joining the tube to the pipe. In such piping system, for example, a pipe includes an inserting end portion on one axial side thereof wherein an annular engagement projection is formed on and around an outer peripheral surface. Then, the inserting end portion of the pipe is inserted and fitted in the connector so that the annular engagement projection snap-engages with the connector to provide locking relation between the pipe and the connector, thereby connection between the pipe and the connector is completed. A quick connector adapted in this manner comprises a tubular connector housing provided with a tube connecting portion on one axial side thereof and an annular or generally annular retainer. The connector housing also has a retainer holding portion on an opposite axial side thereof, wherein at least one engagement window, for example, a pair of engagement windows are provided in diametrically opposed relation with one another. The retainer has a pipe engagement portion on one axial end portion thereof which is configured so as to be snap-engaged with the annular engagement projection of the pipe, and is fitted in the retainer holding portion to engage with the engagement window. That is, the pipe is inserted in the retainer so that the annular engagement projection of the inserting end portion snap-engages with the retainer. And thereby the pipe is fitted in and connected to the quick connector. The pipe engagement portion is configured mostly in engagement slit formed to extend circumferentially of the retainer on one axial end portion thereof. By the way, in such connecting structure, if an operator does not take care sufficiently to complete connection between the pipe and the connector, the inserting end portion of the pipe might not be fully inserted into the retainer or the connector and the annular engagement projection of the pipe might not snap-engage with the retainer. Thus, the pipe might be in so-called half-fitting relation with respect to the connector. In case of a piping system subject to operation while the pipe is incompletely connected to the connector, as sealing property by a sealing member between the connector and the pipe is insufficient or becomes insufficient, an inner fluid usually leaks out.
Then, for example, as disclosed in JP, A, 11-344182, in order to easily verify complete connection of a pipe to a quick connector, a checker is adapted to provide the connector with a function of verifying complete connection. The checker for verifying complete connection usually has a checker body configured to have inner surface curing along or generally along an outer peripheral surface of a connector housing, and a pair of engagement portions. The checker body is provided with a pull-out portion. The engagement portion is formed integrally on the checker body, more specifically, on opposite ends or opposite end portions respectively of the checker body. The checker is fitted on an outer periphery of the connector housing between engagement windows wherein the engagement portions of the checker snap-engage with one circumferential ends of the engagement windows respectively to restrain movement of the checker in a pull-out direction, with an inner end portion of the engagement portion seating in the engagement slit of the retainer. The checker is configured to be allowable for being pulled out by release of snap-engagement between the engagement portion and the engagement window as a result of the engagement portion deflecting and moving radially outwardly, being pressed by the annular engagement projection, when the pipe is correctly fitted in the connector and the annular engagement projection of the inserting end portion fits in and snap-engages with the engagement slit of the retainer. Accordingly, upon completion of connection work of the pipe and the quick connector, it can be verified that the pipe is completely connected in the quick connector by pulling the checker out of the connector housing with the pull-out portion in a direction perpendicular to an axial direction of the connector housing. If the checker cannot be removed out of the connector housing when the checker is pulled, mostly the pipe is not completely connected to the quick connector. In such case, connection work of the pipe and the quick connector should be again implemented so that the inserting end portion of the pipe is fully inserted in the quick connector.
Meanwhile, the annular engagement projection of the pipe presses the engagement portion of the checker toward a radially outward direction in one axial direction to cause deformation and movement thereof. Accordingly, in such structure as allow the engagement portion of the checker to displace in one axial direction, the engagement portion may be limited to move smoothly radially outwardly when pressed by the annular engagement projection. Then it is fear that the pipe cannot be often correctly connected to the quick connector or pipe connecting work is often ended in spite of incomplete fitting relation between the pipe and the connector. In order to solve this problem, the quick connector may be configured as such that an annular end surface, which is defined on one axial end of the inside of the retainer holding portion or on the border between the inside of the retainer holding portion and the inside of a portion to receive a part of the pipe extruded from the retainer, is located on one axial side from one axial end of the engagement window. And a retainer fitting structure is thereby configured so that one axial end of the retainer contacts with or is located adjacent to the annular end surface and the engagement slit is located in an axial position generally corresponding to one axial end of the engagement window. Then, when the checker is fitted on the connector housing so that the engagement portion of the checker is located axially generally corresponding to the engagement slit of the retainer, the engagement portion of the checker is in contact relation with one axial end of the engagement window, and ceases to be displaced toward one axial direction when pressed by the annular engagement projection of the pipe. Therefore, the engagement portions are assured of being deformed smoothly in an opening direction or in a releasing direction at insertion of the pipe.
However, if the annular end surface on one axial side of the inside of the retainer holding portion is defined on one axial side from one axial end of the engagement window, a step is defined between the annular end surface and one axial end of the engagement window. Consequently, when the pipe is inserted, a groove is defined between the step and the pipe and water remains therein. In case of a metallic pipe, the pipe may be rusted and corroded due to water remaining in the groove. Especially in the case that the connector housing is disposed upright in a direction longitudinally thereof, with an insertion opening or an opposite axial end opening upward and a tube connecting portion downward in fuel piping or any other piping of vehicles, a relatively large amount of water is likely to migrate from outside and remain in the groove, it may eventually cause corrosion of the metallic pipe at an early date.
In order to ensure draining performance of a quick connector to prevent a metallic pipe from corrosion, it is preferred that the annular end surface on one axial side of the inside of the retainer holding portion is defined on an axial position corresponding to one axial end of the engagement window so that no step is defined therebetween. However, in this structure, one axial end of the retainer cannot be located on one axial side from one axial end of the engagement window, and the engagement slit is accordingly located on an opposite axial side from one axial end of the engagement window. Therefore, when the checker is fitted on the connector housing so that the engagement portion of the checker is located in an axial position generally corresponding to the engagement slit of the retainer, a gap is defined between the engagement portion and one axial end of the engagement window. In this arrangement, the engagement portions are apt to be displaced in one axial direction and cannot be deformed smoothly an opening direction when pressed by the annular engagement projection of the pipe. As a result, it is a fear that a pipe connecting work is disturbed.
Accordingly, it is an object of the present invention to provide a quick connector with function of verifying complete connection which has an excellent draining performance and is configured so that an engagement portion of a checker is smoothly deformed in an opening direction when a pipe is connected to the quick connector.